DL/T 540-2024 PDF English
US$235.00 · In stock · Download in 9 secondsDL/T 540-2024: Codes for the inspection of buchholz relay Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid DL/T 540: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| DL/T 540-2024 | English | 235 |
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Codes for the inspection of buchholz relay
| Valid |
| DL/T 540-2013 | English | 130 |
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Rules for the inspection of Buchholz relay
| Obsolete |
| DL/T 540-1994 | English | 399 |
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3 days
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Inspection Regulation on QJ-25, QJ-50, QJ-80 Type Gas Relays
| Obsolete |
Excerpted PDFs (Download full copy in 9 seconds upon purchase)PDF Preview: DL/T 540-2024
DL/T 540-2024: Codes for the inspection of buchholz relay---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/DLT540-2024
DL
ELECTRIC POWER INDUSTRY STANDARD
ICS 29.240
CCS K 45
Replacing DL/T 540-2013
Codes for the Inspection of Buchholz Relay
Issued on: DECEMBER 25, 2024
Implemented on: JUNE 25, 2025
Issued by. National Energy Administration
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative References... 5
3 Terms and Definitions... 5
4 Inspection Conditions... 6
5 Inspection Methods... 7
6 Inspection Requirements... 10
Appendix A (informative) Reference Values of the Setting of the Flow Rate of Buchholz
Relays... 12
Codes for the Inspection of Buchholz Relay
1 Scope
This document specifies the inspection conditions, inspection methods and inspection
requirements, etc. of Buchholz relays for transformers.
This document is applicable to the inspection of Buchholz relays for transformers (hereinafter
referred to as the relays). The inspection of Buchholz relays installed on other oil-filled
electrical equipment may take this document as a reference.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 4208-2017 Degrees of Protection Provided by Enclosure (IP code)
GB/T 7595 Quality of Transformer Oils in Service
DL/T 573-2021 Maintenance Guide for Power Transformers
DL/T 2255 Technical Specification for Buchholz Relay Test Equipment
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 setting of the flow rate
The present oil flow rate value for the operation of the relay signal contact.
3.2 operating value of the flow rate
During the inspection, evenly and steadily increase the flow rate to the steady-state oil flow rate
value, at which, the relay signal contact operates.
3.3 operating value of the gas volume
During inspection, slowly inflate or drain the relay filled with transformer oil, until the gas
volume reaches the value, at which, the relay signal contact operates.
3.4 insulating liquid loss contact
When the transformer continues to lose oil and the oil level drops to near the bottom of the
connecting pipeline, the relay electrical contact operates.
4 Inspection Conditions
4.1 Requirements for Inspection Equipment
4.1.1 The test pipeline of the inspection device shall be consistent with the caliber of the relay
under test, and the accuracy class of the inspection device shall not be lower than Class 2.0.
4.1.2 The technical requirements for the inspection device shall comply with the provisions of
DL/T 2255.
4.1.3 The flow velocity inspection range of the inspection device is. φ25.0.6 m/s ~ 4.0 m/s;
φ50.0.6 m/s ~ 3.0 m/s; φ80.0.6 m/s ~ 2.0 m/s.
4.1.4 The gas volume inspection range of the inspection device is. 0 mL ~ 500 mL.
4.1.5 Inspection parameters for the sealing performance of the inspection device. 0.2 MPa; 20
min.
4.1.6 During inspection, the oil temperature shall be controlled between 25 C ~ 40 C.
4.1.7 Users with special requirements for the inspection device may specify them themselves.
4.2 Requirements for Other Instruments and Equipment
4.2.1 Insulation resistance meter (megohmmeter). output voltage is 1,000 V and maximum
output current is not less than 1 mA.
4.2.2 Withstand voltage tester. frequency is 50 Hz and output voltage is not less than 2,000 V.
4.2.3 DC resistance tester. when the measurement range is 0 ~ 2 , the test current is 100
mA, and the absolute value of the measurement error is not greater than 0.01 .
4.2.4 Vacuum gauge. when the measurement range is 10 Pa ~ 1,000 Pa, the absolute value of
the relative error of the indication is not greater than 10%.
4.2.5 All measuring instruments used for the inspection shall be verified or calibrated.
4.3 Environmental Conditions of Inspection
4.3.1 Ambient temperature. 0 C ~ +40 C.
4.3.2 Relative humidity. 75%.
4.4 Working Medium of Inspection
Transformer oil that complies with GB/T 7595.
5 Inspection Methods
5.1 Appearance and Structural Inspection
5.1.1 The relay nameplate shall be durable and not prone to corrosion; the nameplate shall be
firmly fixed, and the writing shall be clear; the nameplate content shall include the manufacturer
or trademark, product name, model, exit-factory No., serial No. of production standard, contact
capacity and production date, etc.
5.1.2 The surface of the relay housing shall be smooth, without paint peeling or rust; the glass
window scale shall be clear; the outlet terminal shall be structurally intact, with complete
accessories and no damaged threads; the screw shall not be loose, and the vent valve and probe
shall be intact; the oil flow direction mark shall be clear and intact.
5.1.3 The relay outlet terminals shall be clearly marked.
5.1.4 The operation of the vent valve and probe shall be flexible; the operating probe shall be
able to normally disconnect and conduct the dry reed contact.
5.1.5 Parts that need to be rotated shall flexibly move, and without any jamming during
operation.
5.1.6 When the baffle is turned to the end position, the dry reed contact shall be reliably engaged.
5.1.7 If necessary, the following inspections may be carried out.
a) The internal parts of the relay shall be intact, without burrs, metal chips and other
defects; the fasteners shall be firmly connected, the fixing brackets shall be firm and
reliable, and the welds shall be well welded without any lack of weld;
b) The dry reed switch is firmly fixed and has a buffer sleeve; the glass tube shall be
intact without oil leakage, the root lead wire shall be reliably welded, the dry reed
switch pin cannot be bent, and shall be arranged and fixed in an oil-resistant insulating
tube, and the permanent magnet shall be firmly fixed in the frame;
c) The dry reed contact movable piece faces the permanent magnet and remains parallel.
5.2 Insulation Performance Test
5.2.1 Between the outlet terminals of the same dry reed switch, between the outlet terminals
and the ground, and between the outlet terminals without electrical connection, a 1,000 V
insulation resistance meter shall be used to measure the insulation resistance, which shall not
be less than 300 M.
5.2.2 Between the outlet terminals and the ground, and between the outlet terminals without
5.5 Inspection of Operating Value of the Gas Volume
5.5.1 The gas volume operating range of the φ50 and φ80 relays is 250 mL ~ 300 mL; the gas
volume operating range of the φ25 relay with the gas volume alarm function is 200 mL ~ 250
mL.
5.5.2 After the relay is filled with transformer oil, close both ends and horizontally place it.
When measuring the light gas signal contact, there shall be no signal output. Open the relay
vent valve and slowly inflate or drain the relay, until a signal action is output. Measure the
volume of the discharged oil, which is the operating value of the gas volume of the relay. Repeat
the inspection three times, and the relay’s operating value each time shall meet the requirements
of 5.5.1.The absolute value of the difference between the three measured operating values and
the gas volume scale value on the relay window shall not be greater than 10% of the operating
value.
5.5.3 When the operating value of the gas volume of the relay does not meet the requirements
in the inspection, if the conditions are met, adjustments can be made to meet the requirements.
5.6 Inspection of Insulating Liquid Loss Contact
The inspection of the insulating liquid loss contact can be simultaneously carried out with the
inspection of the operating value of the gas volume. When the relay is full of transformer oil,
measure the insulating liquid loss contact, and there shall be no signal output. After the
inspection of the operating value of the gas volume is completed, the relay continues to drain
oil, until when it is close to the bottom of the connecting pipeline, there shall be a signal action
output.
5.7 Inspection of Reverse Oil Flow
At the maximum setting of the flow rate of the relay, apply reverse shock 3 times, each time
lasting 5 minutes. There shall be no deformation, displacement or damage to the components
and parts in the relay. Then, carry out the inspection of the operating value of the flow rate, the
inspection of the operating value of the gas volume and the insulation performance test again,
and its performance shall still meet the requirements.
5.8 Inspection of Sealing Performance
5.8.1 Inspection of positive pressure sealing performance
Fill the relay with transformer oil, pressure it to 0.2 MPa, stabilize the pressure for 20 minutes,
and then, check the vent valve, probe, dry reed switch, float, outlet terminal, housing and sealing
parts, which shall have no leakage.
5.8.2 Inspection of vacuum sealing performance
Evacuate the inside of the relay to an absolute pressure of not higher than 133 Pa, and maintain
it for 5 minutes. While maintaining the vacuum state, fill the inside of the relay with transformer
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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